Quality of vitamin K antagonist control and outcomes in atrial fibrillation patients: a meta-analysis and meta-regression

Time-in-therapeutic-range defined warfarin and direct oral anticoagulants in atrial fibrillation: a Nationwide Cohort Study

BACKGROUND

Little is known how individual time-in-therapeutic-range (TTR) impacts the effectiveness and safety of warfarin therapy compared to direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF).

OBJECTIVE

To compare the effectiveness and safety of standard dose DOACs to warfarin in patients with AF, while categorizing warfarin treated patients into quartiles based on their individual TTR.

MATERIALS AND METHODS

We conducted a nationwide study including all patients with new-onset AF between 2011 and 2018 in Finland. Hazard ratios (HR) were calculated using Cox regression analysis with the inverse probability of treatment weighted method to assess the risks of ischaemic stroke (IS), intracranial haemorrhage (ICH) and mortality for users of apixaban (n = 12,426), dabigatran (n = 4545), rivaroxaban (n = 12,950) and warfarin (n = 43,548).

RESULTS

The median TTR for warfarin users was 72%. Compared to the second best TTR quartile (reference), the risk of IS was higher in the two poorest TTR quartiles, and lower in the best TTR quartile and on rivaroxaban [2.35 (95% confidence interval, 1.85-2.85), 1.44 (1.18-1.75), 0.60 (0.47-0.77) and 0.72 (0.56-0.92)]. These differences were non-significant for apixaban and dabigatran. HR of ICH was 6.38 (4.88-8.35) and 1.87 (1.41-2.49) in the two poorest TTR groups, 1.44 (1.02-1.93) on rivaroxaban, and 0.58 (0.40-0.85) in the best TTR group compared to the reference group. Mortality was higher in the two poorest TTR groups and lowest in the best TTR group.

CONCLUSIONS

The outcome was unsatisfactory in the two lowest TTR quartiles - in half of the patients treated with warfarin. The differences between the high TTR groups and standard dose DOACs were absent or modest.

Stability of Anticoagulation Following Acenocoumarin in Stroke Patients: Role of Pharmacogenomics and Acquired Factors

OBJECTIVE

Pharmacogenomics plays an important role in drug metabolism. A stable anticoagulation is important for primary and secondary prevention of cardioembolic stroke and cerebral venous sinus thrombosis (CVST). We report the role of cytochrome P450 ( CYP2C9*2/*3 ) and vitamin K epoxide reductase subunit 1 ( VKORC1 ) genotypes and acquired causes in maintaining stability of anticoagulation following acenocoumarin in cardioembolic stroke and CVST.

METHODS

The study comprised 157 individuals with cardioembolic stroke and CVST who were on acenocoumarin. Their comorbidities, comedication, and dietary habits were noted. Prothrombin time and international normalized ratio (INR) were measured during follow-up, and the coagulation status was categorized as stable (>50% occasions in therapeutic range) and unstable (>50% below and above therapeutic range). Genotyping of VKORC1 , CYP2C9*2 , and CYP2C9*3 was done by polymerase chain reaction-restriction fragment length polymorphism. Bleeding and embolic complications were noted. The predictors of unstable INR were evaluated using multivariate analysis.

RESULTS

INR was stable in 47.8% and unstable in 52.2% of patients. Patients with mutant genotypes required low dose of acenocoumarin. The predictors of unstable INR were metallic valve (odds ratio [OR] 4.07, 95% confidence interval [CI] 1.23-13.49, P = 0.02), use of digoxin (OR 0.031, 95% CI 0.13-0.74, P = 0.09), proton pump inhibitor (OR 0.23, 95% CI 0.06-0.91, P = 0.037), sodium valproate (OR 0.22, 95% CI 0.05-0.85, P = 0.029), and CYP2C9*2 genotype (OR 5.57, 95% CI 1.19-26.06, P = 0.02).

CONCLUSIONS

Variant genotypes of VKORC1 , CYP2C9*2 , and CYP2C9*3 required lower dose of acenocoumarin, and CYP2C9*2 was associated with unstable INR. Comedication is a modifiable risk factor that needs attention.

Anticoagulation control among patients on vitamin K antagonists in nine countries in Sub-Saharan Africa

Vitamin K antagonists (VKA) is the primary anticoagulant in most settings of Sub-Saharan Africa. Understanding the quality of anticoagulation services in the continent is vital in optimising the intended benefits. This study assessed the quality of anticoagulation and associated factors among VKA-treated patients in nine SSA countries. We conducted a retrospective cohort study of randomly selected patients on anticoagulation from 20 clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania, and South Africa. Eligible participants were those on VKAs for at least three months and with at least four international normalised ratios (INR) results in 2019-2021. We report the proportion of INR values in the therapeutic range, time-in-therapeutic range (TTR) using the Rosendaal method, and the proportion of patients with TTR ≥ 65% (optimal anticoagulation). The mean age was 51.1(16.1) years, and 64.2% were women. The most common indications for VKA included venous thromboembolism (29.6%), prosthetic valves (26.7%) and atrial fibrillation/flutter (30.1%). We analysed 6743 INR tests from 1011 participants, and of these, 48.5% were sub-therapeutic, 34.1% therapeutic, and 17.4% were supratherapeutic relative to disease-specific reference ranges. TTR was calculated for 660 patients using 4927 INR measurements. The median (interquartile range [IQR]) TTR was 35.8(15.9,57.2) %. Optimal anticoagulation control was evident in 19.2% of participants, varying from 2.7% in Tanzania to 23.1% in Ethiopia. The proportion of patients with TTR ≥ 65% was 15,4% for prosthetic heart valves, 21.1% for venous thromboembolism and 23.7% for atrial fibrillation or flutter. Countries with universal health coverage had higher odds of optimal anticoagulation control (adjusted odds ratio (aOR) 1.79, 95% confidence interval [CI], 1.15- 2.81, p = 0.01). Patients on VKAs for different therapeutic indications in SSA had suboptimal TTR. Universal health coverage increased the odds of achieving TTR by 79%. The evidence calls for more intensive warfarin management strategies in SSA, including providing VKA services without out-of-pocket payments.

The quality of pharmacist-led community warfarin management across 2 provinces in Canada: A cross-sectional observational study

Background

Guidelines for anticoagulation management services recommend personnel be specially trained in warfarin management and suggest using tools such as decision-support software. To date, there have been no Canadian studies documenting the quality of warfarin management using a similar guideline recommended approach.

Methods

A cross-sectional, retrospective observational study was conducted to measure the quality of pharmacist-led warfarin management using point-of-care international normalized ratio (INR) testing and decision-support software in various ambulatory settings in Canada. Settings included 4 family health teams in Ontario and 40 community pharmacies across Nova Scotia. Quality was measured using time in therapeutic range (TTR) and was reported in 3 manners: mean TTR, median TTR and time-weighted mean TTR.

Results

The primary outcome included 963 patients. The combined mean and median TTR for the 2019 Ontario family health teams and Nova Scotia pharmacies was 74.2% and 77.3% (interquartile range 64%-87.9%), respectively. The time-weighted mean TTR was 76.3%.

Discussion

To the best of our knowledge, the TTR achieved by this model of care is the highest reported in Canadian general practice. Since Thrombosis Canada defines good-quality warfarin management as a TTR of 60% or greater, and many studies have reported an association between higher TTR values and lower rates of thrombosis and hemorrhage, this model of care may have significant benefits for patients.

Conclusion

This study demonstrates the high quality of anticoagulation management provided by specially trained pharmacists using point-of-care INR testing and decision-support software. These results support expanded access to this service for all Canadians. Can Pharm J (Ott) 2024;157:xx-xx.

Vitamin-K-antagonist phenprocoumon versus direct oral anticoagulants in patients with atrial fibrillation: a real-world analysis of German claims data

OBJECTIVES

Direct oral anticoagulants (DOACs) were introduced based on randomised controlled trials (RCTs) comparing them to vitamin-K-antagonist (VKA) warfarin. In Germany, almost exclusively phenprocoumon is used as VKA. RCTs with phenprocoumon being absent we analysed the benefits and harms of DOACs and phenprocoumon for patients with atrial fibrillation (AF) in a real-world setting.

DESIGN

In a retrospective observational cohort study, claims data covering inpatient and outpatient care from 2015 to 2019 were analysed by Cox regression and propensity score matching (PSM).

SETTING

Data from a group of small-sized to medium-sized health insurance companies in Germany.

PARTICIPANTS

We analysed datasets of 71 961 patients with AF and first prescription of phenprocoumon (n=20 179) or DOAC in standard dose (n=51 782). Patients with reduced dose of DOACs were excluded (n=21 724).

OUTCOME MEASURES

Outcomes were thromboembolic events, major bleeding and death during a 12-month follow-up period.

RESULTS

The regression analysis widely showed similarity between phenprocoumon and standard dose DOACs regarding effectiveness and safety. There were only three statistically significant differences: a lower bleeding risk with composite DOACs and apixaban (HR (95% CI) = 0.67 (0.59 to 0.76) and 0.54 (0.46 to 0.63), respectively) and a higher risk of death with rivaroxaban (1.21 (1.10 to 2.34)). The analysis after PSM was consistent with the first two results regarding composite DOACs and apixaban (number needed to treat, NNT 101 and 78) and showed a lower bleeding risk with rivaroxaban (NNT 156). Absolute differences were small.

CONCLUSIONS

The small superiority or non-inferiority of DOACs over warfarin seen in the RCTs might not translate into relevant advantages of DOACs over phenprocoumon. To confirm the hypothesis, an RCT with phenprocoumon is needed. Next to the safety and effectiveness assessments other factors might also play a substantial role in the decision on the right OAC for stroke prevention.

Warfarin anticoagulation management during the COVID-19 pandemic: The role of internet clinic and machine learning

Background: Patients who received warfarin require constant monitoring by hospital staff. However, social distancing and stay-at-home orders, which were universally adopted strategies to avoid the spread of COVID-19, led to unprecedented challenges. This study aimed to optimize warfarin treatment during the COVID-19 pandemic by determining the role of the Internet clinic and developing a machine learning (ML) model to predict anticoagulation quality.

Methods: This retrospective study enrolled patients who received warfarin treatment in the hospital anticoagulation clinic (HAC) and “Internet + Anticoagulation clinic” (IAC) of the Nanjing Drum Tower Hospital between January 2020 and September 2021. The primary outcome was the anticoagulation quality of patients, which was evaluated by both the time in therapeutic range (TTR) and international normalized ratio (INR) variability. Anticoagulation quality and incidence of adverse events were compared between HAC and IAC. Furthermore, five ML algorithms were used to develop the anticoagulation quality prediction model, and the SHAP method was introduced to rank the feature importance.

Results: Totally, 241 patients were included, comprising 145 patients in the HAC group and 96 patients in the IAC group. In the HAC group and IAC group, 73.1 and 69.8% (p = 0.576) of patients achieved good anticoagulation quality, with the average TTR being 79.9 ± 20.0% and 80.6 ± 21.1%, respectively. There was no significant difference in the incidence of adverse events between the two groups. Evaluating the five ML models using the test set, the accuracy of the XGBoost model was 0.767, and the area under the receiver operating characteristic curve was 0.808, which showed the best performance. The results of the SHAP method revealed that age, education, hypertension, aspirin, and amiodarone were the top five important features associated with poor anticoagulation quality.

Conclusion: The IAC contributed to a novel management method for patients who received warfarin during the COVID-19 pandemic, as effective as HAC and with a low risk of virus transmission. The XGBoost model could accurately select patients at a high risk of poor anticoagulation quality, who could benefit from active intervention.

Vitamin K-dependent anticoagulant use and level of anticoagulation control in sub-Saharan Africa: protocol for a retrospective cohort study

BACKGROUND

Given that vitamin K-dependent anticoagulants (VKAs) will continue to be the primary anticoagulant in Africa for a long time, understanding the quality of anticoagulation services in the continent is vital for optimising the intended benefits. Notably, a few small studies have assessed the quality of anticoagulation in sub-Saharan Africa (SSA) countries. This study will describe the current VKA use and anticoagulation control among patients in selected SSA countries.

METHODS AND ANALYSIS

We plan to review the 2019 anticoagulation data of a cohort of 800 random patients from 19 selected clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania and South Africa. We expect at least one participating site to enrol 100 participants in each country. Eligible participants will be those on VKAs for at least 3 months and with at least four international normalised ratio (INR) results. We will document the indications, type and duration of VKA use, sociodemographic factors, coexisting medical conditions, concurrent use of drugs that interact with warfarin and alcohol and tobacco products. The level of anticoagulation control will be determined by calculating the time-in-therapeutic range (TTR) using the Rosendaal and the Percent of INR in TTR methods. A TTR of less than 65% will define a suboptimal anticoagulation control.

ETHICS AND DISSEMINATION

This study was approved by the Ministry of Health and Wellness Ethics Committee (HPDME13/8/1) in Botswana and local research ethics committees or institutional review boards of all participating sites. As the study collects data from existing records, sites applied for waivers of consent. We will disseminate research findings through peer-reviewed scientific publications.

Tele-pharmacy Anticoagulation Clinic During COVID-19 Pandemic: Patient Outcomes

Introduction: It is well-established that clinical pharmacist-managed anticoagulation services achieve superior anticoagulation control, with a positive impact. At King Abdulaziz Medical City (KAMC), Riyadh, Saudi Arabia, the structure of anticoagulation management is a pharmacist-managed specialty service. With the current COVID-19 situation, measures were taken to assure the continuity of patient care by establishing tele-pharmacy anticoagulation clinics. Materials and Methods: This was a prospective study with patients prescribed anticoagulation and followed up for 3 months. Since establishing the anticoagulation virtual clinic in March 2020, 270 patients were recruited in the study. The data collected included age, gender, comorbidities, indication for anticoagulation, intended duration of treatment, warfarin dose, testing of International Normalized Ratio (INR), INR target, range of INR values, time INR that was within the therapeutic range (TTR), and complications of therapy (bleeding and/or bruises). The patients were asked to complete the pharmacist satisfaction survey (PSS) after their consultation to assess patient satisfaction with the new virtual consultation system. Linguistic and cultural validation was conducted for the questionnaire. Results: A total of 270 patients were included in the study. The mean percentage of overall INR values in the range was 59.39% ± 32.84, and the mean time with the overall INR was within the therapeutic range 57.81% ± 32.08. Thirty-one percent of the sample had good anticoagulation control (time in therapeutic range >70%). The median satisfaction score was 32 (IQR 28-36) with a maximum score of 40. Conclusion: This is the first study to assess the tele-pharmacy anticoagulation clinic's efficiency and patient satisfaction in Saudi Arabia during the COVID-19 pandemic. This type of consultation was as effective as face-to-face consultations. The study also highlighted that though the reduction in the cost of care was not substantial, there was a significant increase in resource (clinical pharmacist) utilization as a result of this model. The adoption of tele-pharmacy resulted in time savings for the clinical pharmacists who can be utilized in many other improvement projects in adult ambulatory clinics to ensure the delivery of better quality and safe patient care.

Randomized controlled clinical trials versus real-life atrial fibrillation patients treated with oral anticoagulants. Do we treat the same patients?

BACKGROUND

The aim of the study was to compare clinical characteristics of real-life atrial fibrillation (AF) patients with populations included in randomized clinical trials (ROCKET AF and RE-LY).

METHODS

The analysis included 3528 patients who are participants of the ongoing, multicentre, retrospective CRAFT study. The study is registered in ClinicalTrials.gov: NCT02987062. The study is based on a retrospective analysis of hospital records of AF patients treated with vitamin K antagonists (VKAs) (acenocoumarol, warfarin) and non-vitamin K oral anticoagulants (NOACs) (dabigatran, rivaroxaban). CHADS2 score was used for risk of stroke stratification.

RESULTS

VKA was prescribed in 1973 (56.0%), while NOAC in 1549 (44.0%), including dabigatran - 504 (14.3%) and rivaroxaban - 1051 (29.8%), of the 3528 patients. VKA patients in the CRAFT study were at significantly lower risk of stroke (CHADS2 1.9 ± 1.3), compared with the VKA population from the RE-LY (2.1 ± 1.1) and the ROCKET-AF (3.5 ± 1.0). Patients in the CRAFT study treated with NOAC (CHADS2 for patients on dabigatran 150 mg - 1.3 ± 1.2 and on rivaroxaban - 2.2 ± 1.4) had lower risk than patients from the RE-LY (2.2 ± 1.2) and the ROCKET AF (3.5 ± 0.9).

CONCLUSIONS

Real-world patients had a lower risk of stroke than patients included in the RE-LY and ROCKET AF trials.

The short-term effect of the COVID-19 pandemic on the management of warfarin therapy

Aim    The aim of this study was to investigate the short-term effect of the COVID-19 pandemic on the management of warfarin therapy used for atrial fibrillation (AF) and prosthetic valve disease.Material and methods    The study included 139 Atrial fibrillation (AF) patients and 173 prosthetic valve patients (PVP) who were using warfarin. The time in therapeutic range (TTR), International Normalized Ratio (INR) averages, the numbers of INR tests, and the non-adherence to INR monitoring (NIM) were compared for the pre-covid period (PCP) and the COVID-19 period (CP). Also, adherence to warfarin therapy was evaluated with a questionnaire.Results    For all patients, the INR values were higher in the CP (2.47 vs 2.60, p<0.001), and the NIM percentage was higher (19.2 % vs 71.5 %, p<0.001) in the CP. The number of INR tests was lower during the CP (p<0.001).The percentage of patients with TTR≥70 % was lower during the CP (41.7 % vs 33 % p=0.017). Subgroup analysis showed that for PVP, TTR values and the percentage of patients with TTR ≥70 % were similar in both the PCP and CP periods. The questionnaire showed that for 94.1 % of respondents, the major cause of NIM in the CP was the COVID-19 pandemic. However, during the CP, adherence to warfarin medication was high (95.5 %).Conclusion    Lower TTR during the COVID-19 pandemic can increase bleeding and thromboembolic cases.Therefore, patients taking warfarin should be followed more closely, and more practical ways should be considered for INR testing.

Patient-related factors associated with oral anticoagulation control: a population-based cohort study

OBJECTIVES

Time in therapeutic range (TTR) of ≥70% is a commonly used indicator of optimal anticoagulation control. This study aimed to determine the patterns and predictors of anticoagulation control in a population-based cohort of new users of warfarin.

METHODS

This was a retrospective cohort study. All adults (age ≥18 years) who had been newly initiated on warfarin therapy between January 2006 and March 2011were selected from administrative health databases. TTR was calculated using the Rosendaal method. Multivariable logistic regression models were used to identify patient-related factors associated with optimal TTR. Predictors of patients spending >30% of time above and below the therapeutic international normalised ratio (INR) range were also examined.

KEY FINDINGS

A total of 6032 patients were included in this study. The mean TTR was 54.1 ± 18.8%, and 82.3% of patients had subthreshold TTR (<70%). Compared with New Zealand Europeans, Māori and Pacific people had decreased odds of achieving optimal TTR and increased odds of spending >30% of time below the therapeutic INR range. Patients aged 65-74 years and 75 years or older had increased odds of achieving optimal TTR but decreased odds of spending >30% of time below the therapeutic INR range than those <65 years. Compared with those living in the least socioeconomically deprived areas, those living in the most deprived areas had decreased odds of achieving optimal TTR.

CONCLUSIONS

Anticoagulation control with warfarin is suboptimal in routine care in New Zealand. Age, ethnicity and deprivation index were significant predictors of TTR. It is important to ensure equitable access to appropriate, high-quality care for those living in deprived areas and those from ethnic minority groups.

Effectiveness and Safety of Rivaroxaban by General Practitioners - A Multicenter, Prospective Study in Japanese Patients With Non-Valvular Atrial Fibrillation (GENERAL)

BACKGROUND

Direct oral anticoagulants have become a standard therapy for non-valvular atrial fibrillation (NVAF). However, little is known about their effectiveness/safety when prescribed by general practitioners to treat high-risk populations such as the elderly, those who are frail or have cognitive dysfunction.Methods and Results:In this multicenter, prospective study, a total of 5,717 NVAF patients (mean age 73.9 years) receiving rivaroxaban were registered by general practitioners, with a maximum 3-year follow up (mean 2.0±0.5 years). The primary endpoint was a composite of stroke and systemic embolism (SE). The annual incidence (per 100 person-years) of stroke/SE was 1.23% and for major bleeding, it was 0.63%. Multivariate analyses identified age ≥75 years (hazard ratio [HR]; 2.67, P<0.001) and history of ischemic stroke (HR; 1.89, P=0.005) as significant risk factors of stroke/SE, with history of major bleeding (HR; 14.9, P<0.001) and warfarin use (HR; 2.15, P=0.002) as risk factors for major bleeding events. Neither cognitive dysfunction, defined by the receipt of anti-dementia medications, nor frailty, evaluated by the classification of the Japanese Long-term Care Insurance system, correlated with stroke/SE or major bleeding events.

CONCLUSIONS

The low incidence of adverse events, including stroke/SE and bleeding, in patients prescribed rivaroxaban by general practitioners supports its use as a safe and efficacious treatment in the standard clinical care of high-risk patient populations.

Anticoagulation Control with Acenocoumarol or Warfarin in Non-Valvular Atrial Fibrillation in Primary Care (Fantas-TIC Study)

Introduction: The use of vitamin K antagonists (VKAs) in non-valvular atrial fibrillation (NVAF) is complicated due to the narrow therapeutic margin they present and their unpredictable dose–response relationship. Most studies are based on warfarin, with the results being extrapolated to acenocoumarol. However, studies comparing the two treatments in terms of the degree of anticoagulation control are scarce, justifying the present study. Main factors associated with poor control of time in therapeutic range (TTR) of anticoagulated patients are also studied. Methods: Cross-sectional study, with real-world data from patients treated in primary care (PC). Data were obtained from the System for the Improvement of Research in PC (SIDIAP) database, covering 60,978 NVAF-anticoagulated patients from 287 PC centres in 2018. Descriptive statistics were derived, and odds ratios were estimated by multivariate logistic regression. Results: 41,430 patients were considered: 93% were being treated with acenocoumarol and 7% with warfarin. There was no difference in poor control of TTR between the two types of VKA treatment, acenocoumarol and warfarin (38.9 vs. 38.4; p = 0.610). Poor anticoagulation control was mainly associated with advanced alcoholism (OR = 1.38), liver failure (OR = 1.37) and intracranial haemorrhage (OR = 1.35) as well as female sex, age < 60 years, cardiovascular history, diabetes mellitus and other variables. Conclusions: There is no association between poor anticoagulation control and the type of VKA treatment administered. Factors associated with poor control of TTR must be considered in clinical practice to improve control and decision-making.

Time in Therapeutic Range for Bivalirudin Among Pediatric Ventricular Assist Device Recipients

Given the adverse event rates involving bleeding and thrombosis among children on ventricular assist devices (VADs), anticoagulant management has become a focal point for quality improvement and innovation. There may be advantages to using direct thrombin inhibitors, such as bivalirudin, though this has not been fully explored. As the percent time in therapeutic range (%TTR) for anticoagulants is classically associated with improved clinical outcomes, we evaluated the %TTR for bivalirudin among pediatric VAD recipients. Using a modification of the Rosendaal method, %TTR was calculated using activated partial thromboplastin time measurements for 11 VAD recipients in the early postoperative period (postoperative days 0-14) and for the duration of VAD support. In the initial 2 weeks after VAD implant, mean %TTR was 68.7 (±13.0). During the entire support course, the mean %TTR improved to 79.6 (±11.0). There was an era effect with improving %TTR in the latter half of the study period. We report very good %TTR for bivalirudin both in the first 2 weeks post implant and this improved over the duration of support. Because %TTR reflects the degree of safety and efficacy in chronic anticoagulation, this relatively high %TTR among a diverse, often critically ill cohort suggests that bivalirudin may be a promising agent. Although this study was underpowered to comprehensively evaluate adverse events on bivalirudin, this represents an important next step for larger scale study.

Impact of anticoagulation status on recanalization and outcome of cerebral venous thrombosis

Effective anticoagulation status may determine the recanalization and outcome of cerebral venous thrombosis (CVT). We report impact of anticoagulation status on recanalization and outcome of CVT. This is a retrospective study on 126 patients with CVT diagnosed on magnetic resonance venography (MRV). Their clinical features and risk factors were noted. The data were retrieved from a prospectively maintained registry, and international normalized ratio (INR) was noted after discharge till 3 months. All the patients were on acenocoumarol. Based on INR value, patients were categorized as Group A (effective anticoagulation INR within the therapeutic range or above) and Group B (ineffective anticoagulation INR > 50% below the therapeutic range). A repeat MRV at 3 months was done for recanalization. Outcome at 3 months was evaluated using modified Rankin Scale (mRS), and categorized as good (mRS ≤ 2) and poor (mRS 2 or more) 101(80.2%) patients were in group A and 25(19.8%) in group B. Their demographic, risk factors, magnetic resonance imaging (MRI) and MRV findings were comparable. On repeat MRV, recanalization occurred in 22/24(91.7%); 15(88%) in group A and 7(100%) in group B. Recanalization was independent of coagulation status. Seven (5.6%) patients died and 107(84.9%) had good outcome; 85(84.2%) in group A and 22(88%) in group B. Kaplan Meier analysis also did not reveal survival or good outcome benefits between the groups. In CVT, outcome and recanalization at 3 months are not dependent on coagulation status. Further prospective studies are needed regarding duration of anticoagulant and its impact on recanalization and outcome.

Implementation and Evaluation of Virtual Anticoagulation Clinic Care to Provide Incessant Care During COVID-19 Times in an Indian Tertiary Care Teaching Hospital

Background: COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-II) has become a global pandemic disrupting public health services. Telemedicine has emerged as an important tool to deliver care during these situations. Patients receiving Vitamin K antagonists (VKA) require structured monitoring which has posed a challenge during this pandemic. We aimed to evaluate the impact of Virtual anticoagulation clinic (VAC), a Telehealth model on the quality of anticoagulation, adverse events, and patient satisfaction vis-a-vis standard Anticoagulation clinic (ACC) care.

Materials and methods: A bidirectional cohort study was conducted in the Department of Cardiology, JSS Hospital, Mysore. Two hundred and twenty-eight patients in the VAC and 274 patients in the ACC fulfilling inclusion criteria were the subjects of the study. Telehealth tools like WhatsApp and telephone were used. Time in therapeutic range (TTR), Percentage of International normalized ratio in range (PINRR), and adverse events were analyzed and compared between the VAC group and the ACC group, between pre-COVID and COVID ACC groups, and between the VAC group and the same pre-COVID cohort. Patient satisfaction was assessed by a questionnaire at the end of 8 months. Descriptive statistics were used for the patient characteristics and inferential statistics for the comparisons between pre-VAC and VAC care.

Results: The mean TTR was 75.4 ± 8.9% and 71.2 ± 13.4% in the VAC group and ACC group, respectively (p < 0.001). The mean PINRR was 66.7 ± 9.4% and 62.4 ± 10.9% in the VAC group and ACC group respectively, (p < 0.001). There was no significant difference in TTR between the VAC group and the same pre-COVID cohort. The TTR differential between the pre-COVID and COVID ACC groups was significant. In either group, no major adverse events were seen. The most common tools used for data exchange were WhatsApp (83%) and SMS (17%). Seventy-four percent of patients were extremely satisfied with the overall VAC care.

Conclusions: Virtual anticoagulation clinic, a telehealth model can be used as an alternative option to deliver uninterrupted anticoagulation care during pandemic times.

Evaluation of Warfarin Anticoagulation at University of Gondar Comprehensive Specialized Hospital, North-West Ethiopia

PURPOSE

To assess the quality of warfarin anticoagulation and its clinical outcomes on patients treated with warfarin at the University of Gondar comprehensive specialized hospital, North-west Ethiopia.

METHODS

We reviewed medical records of patients treated with warfarin between June 1, 2016, and May 30, 2018, at the University of Gondar comprehensive specialized hospital. The quality of anticoagulation was evaluated using the percentage of time spent in the therapeutic range. Data were entered into Statistical Product and Service Solutions (SPSS), version 20. Descriptive statistics were used to describe the socio-demographic and clinical characteristics of study participants. Multivariable logistic regression analysis was performed to identify independent predictors of quality of anticoagulation. Statistical significance was declared when the p-value was less than 0.05 at 95% confidence interval (CI).

RESULTS

From a total of 202 patients' charts reviewed, women accounted for 134 (67.3%). The mean participants' age was 44.33 years (±17.05years SD). The median time spent in the therapeutic range was 37.91 with an IQR of (0.00-65.86). More than two-third (143, (70.8%)) of participants had poor anticoagulation quality (time spent in the therapeutic range is less than 65%). Twenty-seven patients (13.4%) experienced adverse medication events of bleeding and thromboembolic events. Logistic regression analysis showed that potential medication interaction [p= 0.003 95% CI Adjusted odds ratio (AOR): 0.32 (0.152-0.689)] and presence of co-morbidity [p= 0.037 95% CI AOR: 0.70 (1.046-4.105)] were significantly associated with quality of anticoagulation.

CONCLUSION

The quality of warfarin anticoagulation at the University of Gondar comprehensive specialized hospital was poor. A strong effort is needed to improve the quality of anticoagulation. Patients who had other co-morbidity conditions and potentially interacting medication need special attention.

Oral Anticoagulant Adequacy in Non-Valvular Atrial Fibrillation in Primary Care: A Cross-Sectional Study Using Real-World Data (Fantas-TIC Study)

Background: Oral anticoagulants (OAs) are the treatment to prevent stroke in atrial fibrillation (AF). Anticoagulant treatment choice in non-valvular atrial fibrillation (NVAF) must be individualized, taking current guidelines into account. Adequacy of anticoagulant therapy under the current criteria for NVAF in real-world primary care is presented. Methods: Cross-sectional study, with real-world data from patients treated in primary care (PC). Data were obtained from the System for the Improvement of Research in Primary Care (SIDIAP) database, covering 60,978 NVAF-anticoagulated patients from 287 PC centers in 2018. Results: In total, 41,430 (68%) were treated with vitamin K antagonists (VKAs) and 19,548 (32%) NVAF with direct-acting oral anticoagulants (DOACs). Inadequate prescription was estimated to be 36.0% and 67.6%, respectively. Most DOAC inadequacy (77.3%) was due to it being prescribed as a first-line anticoagulant when there was no history of thromboembolic events or intracranial hemorrhage (ICH). A total of 22.1% had missing estimated glomerular filtration rate (eGFR) values. Common causes of inadequate VKA prescription were poor control of time in therapeutic range (TTR) (98.8%) and ICH (2.2%). Conclusions: Poor adequacy to current criteria was observed, being inadequacy higher in DOACs than in VKAs. TTR and GFR should be routinely calculated in electronic health records (EHR) to facilitate decision-making and patient safety.

Rivaroxaban Versus Warfarin for Management of Obese African Americans With Non-Valvular Atrial Fibrillation or Venous Thromboembolism: A Retrospective Cohort Analysis

African Americans (AAs) and obese individuals have increased thrombotic risk. This study evaluated the effectiveness and safety of rivaroxaban versus warfarin in obese, AAs with nonvalvular atrial fibrillation (NVAF) or venous thromboembolism (VTE). Optum® De-Identified Electronic Health Record (EHR) data was used to perform separate propensity-score matched analyses of adult, oral anticoagulant (OAC)-naïve AAs with NVAF or acute VTE, respectively; who had a body mass index≥30kg/m² and ≥12-months EHR activity with ≥1-encounter before OAC initiation. Cox regression was performed and reported as hazard ratios (HRs) with 95% confidence intervals (CIs). For the NVAF analysis, 1,969 rivaroxaban- and 1,969 warfarin-users were matched. Rivaroxaban was not associated with a difference in stroke/systemic embolism versus warfarin (HR = 0.88, 95%CI = 0.60-1.28), but less major bleeding (HR = 0.68, 95%CI = 0.50-0.94) was observed. Among 683 rivaroxaban-users with VTE, 1:1 matched to warfarin-users, rivaroxaban did not alter recurrent VTE (HR = 1.36, 95%CI = 0.79-2.34) or major bleeding (HR = 0.80, 95%CI = 0.37-1.71) risk versus warfarin at 6-months (similar findings observed at 3- and 12-months). Rivaroxaban appeared to be associated with similar thrombotic, and similar or lower major bleeding risk versus warfarin in these obese, AA cohorts.

Real-Life International Normalized Ratio Profile in Patients with Non-Valvular Atrial Fibrillation Prescribed Vitamin K Antagonist

Coagulation status with vitamin K antagonists (VKAs) needs to be monitored carefully to ensure maximal efficacy with minimal complication rates.

Aim. To study the international normalized ratio (INR) values in patients on VKAs in selected area, find out which patient characteristics that is associated with good INR control and calculation of the time in the therapeutic range (TTR) according to the number of INR/Patient.

Material and methods. A total of 200 patients with non-valvular atrial fibrillation prescribed vitamin K antagonist as anticoagulant were evaluated. They were divided into two groups: group I with TTR≥65% (n=93) and group II with TTR<65% (n=107). Stroke and hemorrhagic risks were calculated by means of the CHA2DS2-VASc score and HAS-BLED score, respectively. Presence of comorbid diseases was assessed by the Charlson index. TTR was calculated using Rosendaal method.

Results. Patients in group I (TTR≥65%) were younger (p<0.001), more often men (p<0.074) with a high level of education (p<0.001), had lower stroke and hemorrhagic risks (mean CHA2DS2-VASc score was 1.0 and HAS-BLED score – 0.0), and also had fewer comorbidities (mean Charlson index was 0.0; p<0.001) compared to patients in group II (TTR<65%). The rate of inadequate control with VKAs (TTR<65) was 52%. Multivariate logistic regression analysis was done to see the significant independent predictors for a good INR control i.e. TTR≥65%. It was found that high level of education compared to lower levels is the only significant independent predictor for obtaining good INR control (odds ratio=133, 95% confidence interval 34.24-514.44, p<0.001).

Conclusion. It was found that high level of education compared to lower levels is the only significant independent predictor for obtaining good INR control.

Budget impacts associated with improving diagnosis and treatment of atrial fibrillation in high-risk stroke patients

Aim: Estimate the 3-year budget impact in England from 2016/17 of improving nonvalvular atrial fibrillation management in high-risk stroke patients. Materials & methods: The Academic Health Science Network's AF Business Case Model was used to identify detection, protection (risk assessment and treatment initiation) and perfection (optimized treatment) gaps and to project the budget impact of closing these. Results: Closing all gaps over 3 years could prevent 27,550 strokes. Overall, perfection gap savings were £136,650,962 and protection gap savings were £58,146,171. Detection by screening in year one could cost £149,048,676, but with stroke-prevention savings would be £47,081,047 at 3 years. Thus, total potential savings were £194,797,133 and the cost-adjusted budget impact was £147,716,086. Conclusion: The detection and perfection gaps are key areas for investment.

International normalized ratio control and subsequent clinical outcomes in patients with atrial fibrillation using warfarin

We explored associations between INR measures and clinical outcomes in patients with AF using warfarin, and whether INR history predicted future INR measurements. We included patients in ARISTOTLE who were randomized to and received warfarin. Among patients who had events, we included those with ≥ 3 INR values in the 180 days prior to the event, with the most recent ≤ 60 days prior to the event, who were on warfarin at the time of event (n = 545). Non-event patients were included in the control group if they had ≥ 180 days of warfarin exposure with ≥ 3 INR measurements (n = 7259). The median (25th, 75th) number of INR values per patient was 29 (21, 38) over a median follow-up of 1.8 years. A total of 87% had at least one INR value < 1.5; 49% had at least one value > 4.0. The last INRs before events (median 14 [24, 7] days) were < 3.0 for at least 75% of patients with major bleeding and > 2.0 for half of patients with ischemic stroke. Historic time in therapeutic range (TTR) was weakly associated with future TTR (R² = 0.212). Historic TTR ≥ 80% had limited predictive ability to discriminate future TTR ≥ 80% (C index 0.61). In patients with AF receiving warfarin, most bleeding events may not have been preventable despite careful INR control. Our findings suggest that INRs collected through routine management are not sufficiently predictive to provide reassurance about future time in therapeutic range or to prevent subsequent outcomes, and might be over-interpreted in clinical practice.

Group-based Trajectory Models to Assess Quality of INR Control and Its Association With Clinical Outcomes

Supplemental Digital Content is available in the text.

The Time in Therapeutic Range (TTR) is the gold-standard measure used to assess the quality of oral anticoagulation with vitamin K antagonists. However, TTR is a static measure, and International Normalized Ratio (INR) control is a dynamic process. Group-based Trajectory Models (GBTM) can address this dynamic nature by classifying patients into different trajectories of INR control over time.

Successful Resolution of a Large Left Atrial and Left Atrial Appendage Thrombus with Rivaroxaban

A 79-year-old male was admitted to the hospital for acute exacerbation of heart failure. The patient had history of atrial fibrillation and was planned for cardioversion. Preprocedure transesophageal echocardiogram (TEE) revealed a large multilobulated mobile thrombus in the left atrial appendage. The patient refused warfarin therapy and instead chose to take rivaroxaban. Upon outpatient follow-up, 3 months later, no visible thrombus was appreciated on repeat TEE. This case demonstrates successful resolution of left atrial and left atrial appendage thrombi with the use of rivaroxaban. At present time, limited data is available to support the use of rivaroxaban for treatment of intracardiac thrombi. This case highlights the need for further studies to investigate the outcomes and relative efficiency of use of direct oral anticoagulants (DOACs) in lysis of intracardiac thrombus. The benefits of DOACs compared to the standard of therapy could increase patient compliance, reduce length of stay, and improve treatment efficacy.

Effectiveness and safety of rivaroxaban vs. warfarin in non-valvular atrial fibrillation patients with a non-sex-related CHA2DS2-VASc score of 1

Aims

To compare the effectiveness and safety of standard-dose rivaroxaban (20 mg o.d.) and warfarin in non-valvular atrial fibrillation (NVAF) patients with a non-sex-related CHA2DS2-VASc score of 1.

Methods and results

Analysis of United States Truven MarketScan claims from November 2011 to December 2016 for anticoagulant-naïve NVAF patients with a single non-sex-related stroke risk factor assigned 1-point in the CHA2DS2-VASc score and ≥12-months of continuous medical/prescription insurance coverage prior to the qualifying oral anticoagulant dispensing. Standard-dose rivaroxaban users were 1:1 propensity score-matched to warfarin users. Patients were followed until outcome occurrence, insurance disenrollment, or end of data availability. Primary outcomes included stroke or systemic embolism and major bleeding and were compared using Cox regression and reported as hazard ratios (HRs) with 95% confidence intervals (CIs). In all, 3319 rivaroxaban users were 1:1 propensity score-matched to 3319 warfarin users. Median (interquartile range) duration of follow-up was 1.6 (0.7, 2) years and the most common qualifying stroke risk factor was hypertension (n = 4532, 68.3%). Rivaroxaban was associated with a significant reduction in the 1-year stroke or systemic embolism vs. warfarin (HR 0.41, 95% CI 0.17–0.98), with no significant difference in overall major bleeding (HR 0.74, 95% CI 0.44–1.26) or major bleeding subtypes (HR ranging from 0.33 to 0.78, P &gt; 0.05 for all). Similar results were seen after extending follow-up to 2 years.

Conclusions

Rivaroxaban may lower the rate of stroke or systemic embolism vs. warfarin in NVAF patients with a non-sex-related CHA2DS2-VASc score of 1 without impacting major bleeding.

Quality of INR control and switching to non-Vitamin K oral anticoagulants between women and men with atrial fibrillation treated with Vitamin K Antagonists in Spain. A population-based, real-world study

Background

Worldwide, there is growing evidence that quality of international normalized ratio (INR) control in atrial fibrillation patients treated with Vitamin K Antagonists (VKA) is suboptimal. However, sex disparities in population-based real-world settings have been scarcely studied, as well as patterns of switching to second-line Non-VKA oral anticoagulants (NOAC). We aimed to assess the quality of INR control in atrial fibrillation patients treated with VKA in the region of Valencia, Spain, for the whole population and differencing by sex, and to identify factors associated with poor control. We also quantified switching to Non-VKA oral anticoagulants (NOAC) and we identified factors associated to switching.

Methods

This is a cross-sectional, population-based study. Information was obtained through linking different regional electronic databases. Outcome measures were Time in Therapeutic Range (TTR) and percentage of INR determinations in range (PINRR) in 2015, and percentage of switching to NOAC in 2016, for the whole population and stratified by sex.

Results

We included 22,629 patients, 50.4% were women. Mean TTR was 62.3% for women and 63.7% for men, and PINNR was 58.3% for women and 60.1% for men (p<0.001). Considering the TTR<65% threshold, 53% of women and 49.3% of men had poor anticoagulation control (p<0.001). Women, long-term users antiplatelet users, and patients with comorbidities, visits to Emergency Department and use of alcohol were more likely to present poor INR control. 5.4% of poorly controlled patients during 2015 switched to a NOAC throughout 2016, with no sex differences.

Conclusion

The quality of INR control of all AF patients treated with VKA in 2015 in our Southern European region was suboptimal, and women were at a higher risk of poor INR control. This reflects sex disparities in care, and programs for improving the quality of oral anticoagulation should incorporate the gender perspective. Clinical inertia may be lying behind the observed low rates of switching in patient with poor INR control.

The Quality of Anticoagulation Therapy among Warfarin-Treated Patients with Atrial Fibrillation in a Primary Health Care Setting

Background and objectives: Long-term therapy with oral anticoagulants is recommended for stroke prevention in patients with atrial fibrillation (AF). This study evaluated the quality of anticoagulation therapy among warfarin-treated AF patients in selected primary health care centres in Lithuania. Materials and Methods: This was a retrospective study conducted in nine primary health care centres in Lithuania. Existing medical records of randomly selected adult patients with AF who were treated with warfarin for at least 12 months were reviewed and analysed. Physicians’ decisions to adjust warfarin dose were considered as consistent with the approved warfarin posology if warfarin dose was increased in case of international normalized ratio (INR) <2.0, decreased in case of INR >3.0 or unchanged in case of INR within 2.0 to 3.0. Results: The study population included 406 patients. The mean duration of treatment with warfarin was 5.4 years. The median number of INR measurements per patient per year was 8.0. More than half (57.3%) of available INR values were outside the target range, with 13.6% INR values being above 3.0 and 43.7% INR values—below 2.0. The median time in therapeutic range (TTR) was 40.0%; only 20% of patients had TTR of ≥65%. In about 40% of the cases with INR values outside the target range, no dose corrections were implemented. About 27% of decisions on warfarin dose adjustment were not consistent with the recommended warfarin posology. The median number of INR measurements was lower among patients living in urban areas, while the median TTR was significantly higher in urban patients than in rural patients. In the multivariate regression model, gender, HAS-BLED score and warfarin treatment duration were associated with a TTR of ≥65%. Conclusions: Anticoagulation control is suboptimal in routine clinical practice with a median TTR of 40%. Our findings suggest that there might be a room for improvement of anticoagulation control in primary care.

Triple therapy after PCI - Warfarin treatment quality and bleeding risk

Background

A combination of warfarin, aspirin and clopidogrel is indicated after percutaneous coronary intervention (PCI) in some patients, despite the higher risk of bleeding inferred by this triple therapy.

Objectives

Whether the treatment quality of warfarin measured by iTTR (individual time within therapeutic INR range) is associated with bleeding complications during triple therapy after PCI.

Methods

A retrospective register study consisting of 601 triple treated PCI patients from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR). The cohort was cross-matched with the Swedish Patient Registry for background characteristics and bleeding complications up to 6 months after PCI using ICD10 codes, the Prescribed Drug Registry for ongoing medications, and the national oral anticoagulation registry Auricula for warfarin treatment quality. The patients were grouped into four iTTR groups: <50%, 50–69.9%, 70–84.9% and >85% as well as iTTR above or below 70%.

Results

Of 601 patients, 39 (6.5%) had a bleeding complication (type 2 according to BARC). Bleeding was more common for iTTR<70% compared to iTTR>70%, 28 (9.3%) vs. 11 (3.7%) (p = 0.005). The bleeding frequency increased gradually from the best group, iTTR>85% with four bleeders (3.3%) up to 17 bleeders (13.3%) in the worst group with iTTR<50% (p = 0.003), with a corresponding bleeding rate per 100 treatment years of 8.0 and 44.9, respectively. In multivariate analysis low BMI, HR 1.11 (95% CI 1.01–1.22), a medical history of anemia HR 3.17 (1.16–8.69) and iTTR < 70% HR 2.86 (1.25–6.53) increased the risk of bleeding.

Conclusion

Triple therapy after PCI confers a high risk of bleeding events. Warfarin treatment quality measured by iTTR as well as a medical history of anemia are strong independent predictors of bleeding in these patients. Physicians should pay more attention to iTTR after PCI.

Evaluation of oral anticoagulants with vitamin K epoxide reductase in its native milieu

Warfarin, acenocoumarol, phenprocoumon, and fluindione are commonly prescribed oral anticoagulants for the prevention and treatment of thromboembolic disorders. These anticoagulants function by impairing the biosynthesis of active vitamin K-dependent coagulation factors through the inhibition of vitamin K epoxide reductase (VKOR). Genetic variations in VKOR have been closely associated with the resistant phenotype of oral anticoagulation therapy. However, the relative efficacy of these anticoagulants, their mechanisms of action, and their resistance variations among naturally occurring VKOR mutations remain elusive. Here, we explored these questions using our recently established cell-based VKOR activity assay with the endogenous VKOR function ablated. Our results show that the efficacy of these anticoagulants on VKOR inactivation, from most to least, is: acenocoumarol > phenprocoumon > warfarin > fluindione. This is consistent with their effective clinical dosages for stable anticoagulation control. Cell-based functional studies of how each of the 27 naturally occurring VKOR mutations responds to these 4 oral anticoagulants indicate that phenprocoumon has the largest resistance variation (up to 199-fold), whereas the resistance of acenocoumarol varies the least (<14-fold). Cell-based kinetics studies show that fluindione appears to be a competitive inhibitor of VKOR, whereas warfarin is likely to be a mixed-type inhibitor of VKOR. The anticoagulation effect of these oral anticoagulants can be reversed by the administration of a high dose of vitamin K, apparently due to the existence of a different enzyme that can directly reduce vitamin K. These findings provide new insights into the selection of oral anticoagulants, their effective dosage management, and their mechanisms of anticoagulation.

Quality of Chronic Anticoagulation Control in Patients with Intracranial Haemorrhage due to Vitamin K Antagonists

Introduction

Patients treated with vitamin K antagonists (VKA) are at increased risk of intracranial haemorrhage (ICH). The purpose of our study was to determine the quality of previous anticoagulation control in patients with VKA-associated ICH.

Materials and Methods

We prospectively assessed every consecutive patient admitted to our stroke unit with VKA-associated ICH between 2013 and 2016. Demographic, clinical, and radiological variables, as well as consecutive international normalized ratios (INR) during 7 previous months, were extracted. Time in therapeutic range (TTR), time over range (TOR), time below range (TBR), and percentage of INR within range (PINRR) were calculated.

Results and Discussion

The study population comprised 53 patients. Mean age was 79 years; 42% were women. Forty-eight patients had atrial fibrillation (AF) and 5 mechanical prosthetic valves. Therapeutic or infratherapeutic INR on arrival was detected in 64.4% of patients (95% CI 2.7 to 3.2). TTR was 67.8% (95% CI: 60.2 to 75.6 %) and PINRR was 75% (95% CI: 49.9-100). TOR was 17.2% (95% CI: 10.4 to 23.9% ) and TBR was 17% (95% CI: 10.6 to 23.9%).

Conclusion

VKA-associated ICH happens usually in the context of good chronic anticoagulation control. Newer risk assessment methods are required.

Quality of Anticoagulation With Warfarin at a Tertiary Hospital in Botswana

Warfarin treatment requires regular and proper monitoring to avoid overanticoagulation and at the same time to prevent thromboembolic complications. This study assessed the quality of warfarin anticoagulation at Princess Marina Hospital in Botswana. This cross-sectional study consecutively enrolled patients who were on warfarin for at least 3 months in the outpatient medical clinic. The level of anticoagulation was determined by the time in therapeutic range (TTR) using the Rosendaal method that calculates the percentage of days when the international normalized ratio is in the therapeutic range (2.0-3.0). Poor anticoagulation control was defined as an estimated TTR <65%. We performed univariate and multivariate logistic regression to assess predictors of poor anticoagulation control. Of total, 410 (68.8% women) patients whose median age was 46 (interquartile range [IQR], 35-58) years were enrolled. Indications for warfarin included mechanical heart valves, 185 (45.1%); deep vein thrombosis, 114 (26.8%); and atrial fibrillation, 68 (17.8%). Of the 2004 tests (an average of 4.9 tests per patient) assessed, only 20% of the tests were within the therapeutic range. The median TTR was 30.8% (IQR, 15.2-52.7). Most (85.1%) patients had poor anticoagulation control. Cigarette smoking and pulmonary hypertension perfectly predicted poor anticoagulation. Hypertension was a predictor of poor anticoagulation control (adjusted odds ratio = 2.24; 95% confidence interval: 1.02-4.94). The quality of anticoagulant therapy with warfarin in Botswana patients is poor. The evidence calls for efforts to improve the level of anticoagulation control among patients on warfarin in Botswana.

Rivaroxaban plasma levels in acute ischemic stroke and intracerebral hemorrhage

OBJECTIVE

Information about rivaroxaban plasma level (RivLev) may guide treatment decisions in patients with acute ischemic stroke (AIS) and intracerebral hemorrhage (ICH) taking rivaroxaban.

METHODS

In a multicenter registry-based study (Novel Oral Anticoagulants in Stroke Patients collaboration; ClinicalTrials.gov: NCT02353585) of patients with stroke while taking rivaroxaban, we compared RivLev in patients with AIS and ICH. We determined how many AIS patients had RivLev ≤ 100ng/ml, indicating possible eligibility for thrombolysis, and how many ICH patients had RivLev ≥ 75ng/ml, making them possibly eligible for the use of specific reversal agents. We explored factors associated with RivLev (Spearman correlation, regression models) and studied the sensitivity and specificity of international normalized ratio (INR) thresholds to substitute RivLev using cross tables and receiver operating characteristic curves.

RESULTS

Among 241 patients (median age = 80 years, interquartile range [IQR] = 73-84; median time from onset to admission = 2 hours, IQR = 1-4.5 hours; median RivLev = 89ng/ml, IQR = 31-194), 190 had AIS and 51 had ICH. RivLev was similar in AIS patients (82ng/ml, IQR = 30-202) and ICH patients (102ng/ml, IQR = 51-165; p = 0.24). Trough RivLev_{(≤137ng/ml)} occurred in 126/190 (66.3%) AIS and 34/51 (66.7%) ICH patients. Among AIS patients, 108/190 (56.8%) had RivLev ≤ 100ng/ml. In ICH patients, 33/51 (64.7%) had RivLev ≥ 75ng/ml. RivLev was associated with rivaroxaban dosage, and inversely with renal function and time since last intake (each p < 0.05). INR ≤ 1.0 had a specificity of 98.9% and a sensitivity of 25.7% to predict RivLev ≤ 100ng/ml. INR ≥ 1.4 had a sensitivity of 59.3% and specificity of 90.1% to predict RivLev ≥ 75ng/ml.

INTERPRETATION

RivLev did not differ between patients with AIS and ICH. Half of the patients with AIS under rivaroxaban had a RivLev low enough to consider thrombolysis. In ICH patients, two-thirds had a RivLev high enough to meet the eligibility for the use of a specific reversal agent. INR thresholds perform poorly to inform treatment decisions in individual patients. Ann Neurol 2018;83:451-459.

Dedicated warfarin care programme results in superior warfarin control in Queensland, Australia

BACKGROUND

Warfarin is used to prevent stroke in patients with atrial fibrillation (AF). Ongoing monitoring of International normalised ratio (INR) and time in therapeutic range (TTR) commonly used to assess the quality of warfarin management are required. Anticoagulant clinics have demonstrated improved TTRs, particularly in countries with poorer control in primary care settings. Reported TTR in Australia has been relatively high; so, it is unknown if benefit would be seen from dedicated warfarin clinics in Australia. The aim of this study was to compare the level of warfarin control in patients managed by their general practitioner (GP) and a warfarin care programme (WCP) by Sullivan Nicolaides Pathology.

METHOD

Retrospective data were collected for AF patients enrolled in the warfarin care programme at WCP, and included patients with INR tests available while managed by their GP. INR tests were used to calculate TTR and frequency of testing for the time managed by GP and WCP, with mean data used for analysis and comparison.

RESULTS

The eligible 200 warfarin patients had a TTR of 69% with GP management and 82% with WCP management (<.0001). Significant differences were also found between GP and WCP management in the percentage of tests in range, total number of tests and frequency of testing. WCP had a reduced time to repeat test at extremes of INR results.

CONCLUSION

Australian warfarin control was good when managed by either GP or WCP, but WCP management increased TTR by 13%. Dedicated warfarin programmes can improve warfarin control and optimise therapy for patients.

Impact of provision of time in therapeutic range value on anticoagulation management in atrial fibrillation patients on warfarin

INTRODUCTION

The importance of time in therapeutic range (TTR) in patients prescribed warfarin therapy for stroke prevention in atrial fibrillation (AF) cannot be overemphasised.

AIM

To evaluate the impact of provision of TTR results during clinic visits on anticoagulation management.

DESIGN

Single-centred, randomised controlled study.

SETTING

Fifteen arrhythmia clinics in Hong Kong.

PATIENTS

AF patients prescribed warfarin.

INTERVENTIONS

Provision of TTR or no provision of TTR.

MAIN OUTCOME MEASURES

A documented discussion between doctors and patients about switching warfarin to a non-vitamin K oral anticoagulant (NOAC).

RESULTS

Four hundred and eighty one patients with AF prescribed warfarin were randomly assigned to (1) a TTR provision group or (2) control. Their mean age was 73.6±12.0 years and 60.7% were men. The mean CHA₂DS₂-VASc score was 3.2±1.6 and the mean HASBLED score was 1.7±1.2. The mean TTR was 63.9%±29.9%. At the index clinic visit, 71 of 481 patients (14.8%) had a documented discussion about switching warfarin to a NOAC. Patients with provision of TTR results were more likely to discuss switching warfarin to a NOAC than controls (19.1% vs 10.6%, P=0.03), especially those with a TTR <65% (35.2% vs 10.6%, P<0.001). A higher proportion of patients with provision of TTR results switched to a NOAC (5.9% vs 4.1%, P=0.49).

CONCLUSIONS

The provision of TTR among patients on warfarin was associated with a discussion about switching from warfarin to a NOAC in those with TTR <65%, but did not result in actual switching to a NOAC, suggesting additional barriers.

DOAC use in patients with chronic kidney disease

Direct oral anticoagulants (DOACs) are increasingly prescribed substances in patients with indication for effective anticoagulation. Patients with chronic kidney disease (CKD) have a high burden of cardiovascular risk and are more likely to develop atrial fibrillation (AF) than patients without CKD. Patients with mild to moderate CKD benefit from DOACs, especially when having intolerance to vitamin K-antagonists (VKA). DOACs may in some cases be considered in patients with rare renal disease and hypercoagulabilic state. DOACs are to a large extent eliminated by renal excretion. Since prospective randomised data in CKD patients are sparse, the decision for anticoagulative therapy is challenging especially in patients with severe renal impairment. The direct factor Xa-inhibitors are approved for use even in patients with an estimated glomerular filtration rate (eGFR) between 15 and 30 ml/min. Careful monitoring of renal function on a regular basis is essential before initiation and after start of DOAC, especially for patients at risk for acute renal failure (elderly, diabetics, patients with preexisting kidney disease). None of the DOACs is approved in CKD patients with end-stage-renal-disease (ESRD) with or without dialysis. DOACs are not recommended for kidney transplant patients under immunosuppression with calcineurin inhibitors. In these patients conventional therapy with VKA is the only option, which has to be monitored closely since it has potential adverse effects.

Quality of Anticoagulation With Warfarin at a Tertiary Hospital in Botswana

Warfarin treatment requires regular and proper monitoring to avoid overanticoagulation and at the same time to prevent thromboembolic complications. This study assessed the quality of warfarin anticoagulation at Princess Marina Hospital in Botswana. This cross-sectional study consecutively enrolled patients who were on warfarin for at least 3 months in the outpatient medical clinic. The level of anticoagulation was determined by the time in therapeutic range (TTR) using the Rosendaal method that calculates the percentage of days when the international normalized ratio is in the therapeutic range (2.0-3.0). Poor anticoagulation control was defined as an estimated TTR <65%. We performed univariate and multivariate logistic regression to assess predictors of poor anticoagulation control. Of total, 410 (68.8% women) patients whose median age was 46 (interquartile range [IQR], 35-58) years were enrolled. Indications for warfarin included mechanical heart valves, 185 (45.1%); deep vein thrombosis, 114 (26.8%); and atrial fibrillation, 68 (17.8%). Of the 2004 tests (an average of 4.9 tests per patient) assessed, only 20% of the tests were within the therapeutic range. The median TTR was 30.8% (IQR, 15.2-52.7). Most (85.1%) patients had poor anticoagulation control. Cigarette smoking and pulmonary hypertension perfectly predicted poor anticoagulation. Hypertension was a predictor of poor anticoagulation control (adjusted odds ratio = 2.24; 95% confidence interval: 1.02-4.94). The quality of anticoagulant therapy with warfarin in Botswana patients is poor. The evidence calls for efforts to improve the level of anticoagulation control among patients on warfarin in Botswana.

Quality of Anticoagulation With Warfarin at a Tertiary Hospital in Botswana

Warfarin treatment requires regular and proper monitoring to avoid overanticoagulation and at the same time to prevent thromboembolic complications. This study assessed the quality of warfarin anticoagulation at Princess Marina Hospital in Botswana. This cross-sectional study consecutively enrolled patients who were on warfarin for at least 3 months in the outpatient medical clinic. The level of anticoagulation was determined by the time in therapeutic range (TTR) using the Rosendaal method that calculates the percentage of days when the international normalized ratio is in the therapeutic range (2.0-3.0). Poor anticoagulation control was defined as an estimated TTR <65%. We performed univariate and multivariate logistic regression to assess predictors of poor anticoagulation control. Of total, 410 (68.8% women) patients whose median age was 46 (interquartile range [IQR], 35-58) years were enrolled. Indications for warfarin included mechanical heart valves, 185 (45.1%); deep vein thrombosis, 114 (26.8%); and atrial fibrillation, 68 (17.8%). Of the 2004 tests (an average of 4.9 tests per patient) assessed, only 20% of the tests were within the therapeutic range. The median TTR was 30.8% (IQR, 15.2-52.7). Most (85.1%) patients had poor anticoagulation control. Cigarette smoking and pulmonary hypertension perfectly predicted poor anticoagulation. Hypertension was a predictor of poor anticoagulation control (adjusted odds ratio = 2.24; 95% confidence interval: 1.02-4.94). The quality of anticoagulant therapy with warfarin in Botswana patients is poor. The evidence calls for efforts to improve the level of anticoagulation control among patients on warfarin in Botswana.

The importance of mean time in therapeutic range for complication rates in warfarin therapy of patients with atrial fibrillation: A systematic review and meta-regression analysis

Background

\Anticoagulation is used for stroke prophylaxis in non-valvular atrial fibrillation, amongst other by use of the vitamin K antagonist, warfarin. Quality in warfarin therapy is often summarized by the time patients spend within the therapeutic range (percent time in therapeutic range, TTR). The correlation between TTR and the occurrence of complications during warfarin therapy has been established, but the influence of patient characteristics in that respect remains undetermined. The objective of the present papers was to examine the association between mean TTR and complication rates with adjustment for differences in relevant patient cohort characteristics.

Methods

A systematic literature search was conducted in MEDLINE and Embase (2005–2015) to identify eligible studies reporting on use of warfarin therapy by patients with non-valvular atrial fibrillation and the occurrence of hemorrhage and thromboembolism. Both randomized controlled trials and observational cohort studies were included. The association between the reported mean TTR and major bleeding and stroke/systemic embolism was analyzed by random-effects meta-regression with and without adjustment for relevant clinical cohort characteristics. In the adjusted meta-regressions, the impact of mean TTR on the occurrence of hemorrhage was adjusted for the mean age and the proportion of populations with prior stroke or transient ischemic attack. In the adjusted analyses on thromboembolism, the proportion of females was, furthermore, included.

Results

Of 2169 papers, 35 papers met pre-specified inclusion criteria, holding relevant information on 31 patient cohorts. In univariable meta-regression, increasing mean TTR was significantly associated with a decreased rate of both major bleeding and stroke/systemic embolism. However, after adjustment mean TTR was no longer significantly associated with stroke/systemic embolism. The proportion of residual variance composed by between-study heterogeneity was substantial for all analyses.

Conclusions

Although higher mean TTR in warfarin therapy was associated with lower complication rates in atrial fibrillation, the strength of the association was decreased when adjusting for differences in relevant clinical characteristics of the patient cohorts. This study suggests that mainly the safety of warfarin therapy increases with higher mean TTR, whereas effectiveness appears not to be substantially improved.

Due to the limitations immanent in the meta-regression methods, the results of the present study should be interpreted with caution. Further research on the association between the quality of warfarin therapy and risk of complications is warranted with adjustment for clinically relevant characteristics.

Clinical Prediction Model for Time in Therapeutic Range While on Warfarin in Newly Diagnosed Atrial Fibrillation

Background

Though warfarin has historically been the primary oral anticoagulant for stroke prevention in newly diagnosed atrial fibrillation (AF), several new direct oral anticoagulants may be preferred when anticoagulation control with warfarin is expected to be poor. This study developed a prediction model for time in therapeutic range (TTR) among newly diagnosed AF patients on newly initiated warfarin as a tool to assist decision making between warfarin and direct oral anticoagulants.

Methods and Results

This electronic medical record–based, retrospective study included newly diagnosed, nonvalvular AF patients with no recent warfarin exposure receiving primary care services through a large healthcare system in rural Pennsylvania. TTR was estimated as the percentage of time international normalized ratio measurements were between 2.0 and 3.0 during the first year following warfarin initiation. Candidate predictors of TTR were chosen from data elements collected during usual clinical care. A TTR prediction model was developed and temporally validated and its predictive performance was compared with the SAMe‐TT₂R₂ score (sex, age, medical history, treatment, tobacco, race) using R² and c‐statistics. A total of 7877 newly diagnosed AF patients met study inclusion criteria. Median (interquartile range) TTR within the first year of starting warfarin was 51% (32, 67). Of 85 candidate predictors evaluated, 15 were included in the final validated model with an R² of 15.4%. The proposed model showed better predictive performance than the SAMe‐TT₂R₂ score (R²=3.0%).

Conclusions

The proposed prediction model may assist decision making on the proper mode of oral anticoagulant among newly diagnosed AF patients. However, predicting TTR on warfarin remains challenging.

Factors influencing warfarin control in Australia and Singapore

INTRODUCTION

Warfarin is widely used for patients with non-valvular atrial fibrillation (NVAF). Variations in warfarin control, as measured by time in therapeutic range (TTR), have been reported across different regions and ethnicities, particularly between Western and Asian countries. However, there is limited data on comparative factors influencing warfarin control in Caucasian and Asian patients. Therefore, the aim of this study was to determine warfarin control and potential factors influencing this in patients with NVAF in Australia and Singapore.

METHODS

Retrospective data was collected for patients receiving warfarin for January to June 2014 in Australia and Singapore. TTR was calculated for individuals with mean patient TTR used for analysis. Possible influential factors on TTR were analysed including age, gender, concurrent co-morbidities, and concurrent medication.

RESULTS

The mean TTR was significantly higher in Australia (82%) than Singapore (58%). At both sites, chronic kidney disease significantly lowered this TTR. Further factors influencing control were anaemia and age<60years in Australia, and vascular disease, CHA₂DS₂-VASc score of 6, and concurrent platelet inhibitor therapy in Singapore.

DISCUSSION

Warfarin control was significantly higher in Australia compared to Singapore, however chronic kidney disease reduced control at both sites. The different levels of control in these two countries, together with patient factors further reducing control may impact on anticoagulant choice in these countries with better outcomes from warfarin in Australia compared to Singapore.

Comparison of all-cause, stroke, and bleed-specific healthcare resource utilization among patients with non-valvular atrial fibrillation (NVAF) and newly treated with dabigatran or warfarin

BACKGROUND

We compared healthcare utilization outcomes and persistence among non-valvular atrial fibrillation (NVAF) patients newly treated with dabigatran or warfarin.

METHODS

Using a nationwide, US administrative claims database, a retrospective matched-cohort of newly diagnosed NVAF patients (age≥18 years) treated with dabigatran or warfarin (propensity score matched 1:1) in 01/01/2011-12/31/2013 was evaluated. All-cause, stroke-, and bleed-specific per patient per month (PPPM) healthcare resource utilization (HCRU), incidence rate of hospitalization for stroke or bleed, 30-day readmission, and persistence were reported.

RESULTS

In total, 18,890 dabigatran patients were matched to corresponding warfarin patients. Compared to warfarin users, dabigatran users PPPM had significantly fewer all-cause hospitalizations (0.04 vs 0.05), total outpatient visits (3.98 vs 5.87), and lower 30-day readmissions (14.5% vs 17.4%, all p < 0.001). Dabigatran users had lower incidence rate for stroke (0.65 vs 1.06) and bleed (1.69 vs 2.20), stroke (0.0006 vs 0.0011, p < 0.001) and bleed-specific hospitalizations (0.002 vs 0.003, p = 0.008), and stroke (0.03 vs 0.04, p < 0.001) and bleed-specific outpatient visits (0.07 vs 0.08, p = 0.018), and significantly lower non-persistence (62.1% vs 66.3%, p < 0.001).

CONCLUSION

Among newly diagnosed newly treated NVAF patients, dabigatran users had significantly lower all-cause, stroke- and bleed-specific HCRU, lower risk of hospitalization for stroke or bleed events, lower 30-day readmissions, and higher persistence than warfarin users.

Effectiveness and Safety of Apixaban, Dabigatran, and Rivaroxaban Versus Warfarin in Patients With Nonvalvular Atrial Fibrillation and Previous Stroke or Transient Ischemic Attack

BACKGROUND AND PURPOSE

Limited real-world data exist comparing each non-vitamin K antagonist oral anticoagulant (NOAC) to warfarin in patients with nonvalvular atrial fibrillation who have had a previous ischemic stroke or transient ischemic attack.

METHODS

Using MarketScan claims from January 2012 to June 2015, we identified adults newly initiated on oral anticoagulation, with ≥2 diagnosis codes for nonvalvular atrial fibrillation, a history of previous ischemic stroke/transient ischemic attack, and ≥180 days of continuous medical and prescription benefits before anticoagulation initiation. Three analyses were performed comparing 1:1 propensity score-matched cohorts of apixaban versus warfarin (n=2514), dabigatran versus warfarin (n=1962), and rivaroxaban versus warfarin (n=5208). Patients were followed until occurrence of a combined end point of ischemic stroke and intracranial hemorrhage (ICH) or major bleed, switch/discontinuation of index oral anticoagulation, insurance disenrollment, or end of follow-up. Mean follow-up was 0.5 to 0.6 years for all matched cohorts.

RESULTS

Using Cox regression, neither apixaban nor dabigatran reduced the combined primary end point of ischemic stroke or ICH (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.33-1.48 and HR, 0.53; 95% CI, 0.26-1.07) and had nonsignificant effect on hazards of major bleeding (HR, 0.79; 95% CI, 0.38-1.64 and HR, 0.58; 95% CI, 0.26-1.27) versus warfarin. Rivaroxaban reduced the combined end point of ischemic stroke or ICH (HR, 0.45; 95% CI, 0.29-0.72) without an effect on major bleeding (HR, 1.07; 95% CI, 0.71-1.61). ICH occurred at rates of 0.16 to 0.61 events per 100 person-years in the 3 NOAC analyses, with no significant difference for any NOAC versus warfarin.

CONCLUSIONS

Results from our study of the 3 NOACs versus warfarin in nonvalvular atrial fibrillation patients with a previous history of stroke/transient ischemic attack are relatively consistent with their respective phase III trials and previous stroke/transient ischemic attack subgroup analyses. All NOACs seemed no worse than warfarin in respect to ischemic stroke, ICH, or major bleeding risk.